Flexible display devices have many advantages, for example, impact resistance, high shock resistance, light weight, small size, convenience to carry, etc. At present, main flexible display materials may be roughly classified into three types: electronic paper (or flexible electrophoretic display), flexible Organic Light-Emitting Diodes (OLED) and flexible liquid crystals, etc.
A flexible display device includes a display substrate including a flexible base substrate and a structure located on the flexible base substrate, wherein the flexible base substrate is a polyimide (PI) base substrate, a polyethylene glycol terephthalate (PET) base substrate, etc; and the structure on the flexible base substrate includes thin film transistors (TFTs). Usually, the display substrate of the flexible display device in the prior art is provided therein with insulating layers, for example, gate insulating layer, interlayer insulating layer and passivation layer. The insulating layers are generally made of SiNx or SiOx materials, so the insulating layers have poor flexibility. As a result, it is likely to fracture the insulating layers when the flexible display device is bent, so that the TFTs on the display substrate of the flexible display device are easy to be damaged. For example, the generated stress when the display substrate is bent may result in the fracture of the TFTs, so the performances of the TFTs will certainly be influenced, thereby influencing the reliability of the flexible display device and causing adverse effects on the display quality.